The present invention relates to the field of training ammunition and, more specifically, to a non-pyrotechnic training ammunition cartridge having a projectile that can mark its point of impact both by day and by night.
Military gunners often fire their weapons at long range in military training areas that include grass, vegetation and low lying trees. Hence, while there is some value in firing projectiles that directly mark a target on impact, the morphology and terrain on a military range frequently preclude gunners from having direct views of the actual impact points.
Good military training devices should simulate the effects of live fire high-explosive detonations. In combat such detonations generate visual and near infra-red light and heat, forming a multi-spectral signature. High explosive detonations also produce smoke plumes. The light and heat resulting from high-explosive detonations can be detected by an array of fire control devices used by the military. The smoke plumes are also visible to the naked eye.
The target locating devices used in the military have visual cameras and cameras that operate in the near and/or far IR spectrum. Accordingly it is desired that practice ammunition simulate the effects seen in combat and that practice ammunition generate multi-spectral marking signatures, upon impact, that can be viewed by these cameras.
Currently, military forces use a wide array of technologies to detect and identify targets and adjust fire. Traditionally, they have used pyrotechnic devices in training ammunition allowing gunners to trace their fire and mark their targets. These pyrotechnic devices produce smoke and heat plumes from combustion of pyrotechnic compounds. Unfortunately, these pyrotechnic devices frequently generate dangerous unexploded ordnance (UXO) and pyrotechnic compounds frequently have chemicals that contaminate ground water. Ground water contamination and UXO are expensive to remediate. Additionally, pyrotechnic devices can also start range fires, leading to destruction of ecosystems and soil erosion.
To prevent the generation of UXO and range fires during training, inert practice ammunition cartridges have been developed which do not employ energetic pyrotechnics to trace the flight and mark the impact of the projectile. For example, low density, dry fine powders have been used to create a plume for visibly marking the target upon impact. This marking agent has been used, for example, in the US Army's M781 40 mm low velocity cartridge.
Chemi-luminescent technology, such as that taught in the U.S. Pat. No. 6,619,211, has also been used to mark both the trace and point of impact by night. Two liquid chemical components are placed in separate frangible compartments or ampoules that break open on setback when the projectile is fired from a weapon. This allows the components to mix and luminesce, thereby providing a visible trace during flight if the projectile ogive is transparent or translucent, and marking the point of impact when the projectile strikes the target. As disclosed in this patent, the frangible ampoules are located near center of a projectile's axis of rotation and, when the liquids are released from their compartments, they tend to destabilize the projectile as it spins, resulting in projectile yaw.
The U.S. Pat. No. 8,438,978 discloses a multi-spectral marking projectile having chemical components that are caused to mix upon setback, due to the initial acceleration and the centrifugal forces, and thereby produce an exothermic reaction which emits heat during the flight of the projectile. This serves to warm the chemi-luminescent materials during flight and provides an Infrared marking signature when the projectile strikes the target.
The U.S. Pat. No. 7,055,438 also discloses a flameless tracer/marker utilizing heat marking chemicals in addition to chemo-luminescent materials.
The subject matter of the various patents noted above is incorporated herein by reference.